Phone support jobs are the worst. My mother does phone support for the Postal Service and she's always getting calls from furious people shouting "How could you lose my paperwork/medicine/irreplaceable antique like that?" etc., etc., etc. If she's had a bad day she'll say "Yeah, you really should have used UPS, only an idiot would have entrusted that to the Post Office" and hang up.

Pro tip: If you actually need help, don't scream vulgarities at a person who had nothing to do with causing your problem in the first place.